Fuse



Jude 7, 1932*. C, R|NGWALD I 1,862,317

FUSE

Filed Dec. 23. 1927 2 sheets-Sheet 1 Suv/wz iff?,

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June 7, 1932.

c. RINGWALD 1.862.317

` FUSE Filed Dec. 2 snee-tszsneet 2 ryl Patented June 7, 1932 UNITED STATES PATENT OFFICE CLARENCE RINGWALD, OF SOUTH BEND, INDIANA, ASSIGNOR, BY MESNE ASSIGNMENTS,

TO SCHWEITZER & CONRAD, INC., OF CHICAGOILLINOIS, A CORPORATION 0F DELA- WARE FUSE

HEISSUED Application led December 23, 1927. Serial No. 242,137.

" ployed. The chief reason for this distinction resides in two things: first, the amount, i. e., the mass of metal which will be blown, i. e., fused and vaporized, and, second, the limiting strength of the Circumambient medium, i. e., air, in the case of the usual small unfilled fuse.

Numerous schemes have been devised for increasing the distance between terminals when the fuse blows so as to diminish the amount, i. e., mass of metal to be blown to give a certain clearance. Also various schemes of providing a surrounding envelope of a medium of higher dielectric strength than air have been proposed. In some cases both means have been provided.

My invention, while it may be embodied in a fuse wherein the terminals are separated to a greater extent upon blowing of the fusible elem-ent, is primarily concerned with the provision of a surrounding medium of greater strength than air and which has certain inherent benefici al effects in the extinction of an arc and in the application of this medium to the containerso as to maintain the desired relationbetween this substance and the active fuse element.

Where a mass of metal between two conducting terminalsis vaporized, a How of conducting electrons appears to be maintained. Inthe case of metal vapors, the conduction appears to occur very muchas in the case of solid conductors, i. e., by a flow of electrons through'the adjacent molecules. In the case of the breakdown of air, it` appears that there are two things which conduct the current flow. First, the molecules of gas are broken down to Jforce electrons from their orbits, and, second, a certain amount of metal vapor is freed from the terminals. In the case of a corona or brush discharge substantially no metal vapor is released and, hence, a relatively high resistance is maintained in the arc or spark. If the metal vapor can be kept from forming, or if it could be eliminated, the air would continue to aEord a fairly high re- 60 sistance, even though it were broken down.

I have conceived the possibility of surrounding the arc with a substance which will initially afford a high resistance to current How, i. e., constitute of itself an excellent in`. 05 snlating medium of very high dielectric strength, and which, in conjunction with the vaporized metal of the electric arc, will tend to react to form a compound of such high resistance as to bind the electrons in unions 7o which will resist disruption and, hence, resist current flow with consequent stoppage of the arc.

Such compounds are generally disintegrat- -ed in the electric arc and, hence, if chilling can be occasioned at the same time that the compounds are formed, or if the energy of the are can be sufficiently dissipated to let these compounds cut down the How of current, the arc can'be extinguished in a simple so and eiticacious manner.

For example, assume that when a metal vapor is formed I could combine the metal with oxygen to form a high resistance oxide.

If this reaction could be carried on more rapidly than metal vapor could be released, it will be possible at once to snap out an arc positively and edectively.

So far, I have not found it possible in atmospheric air to provide suiiciently rapid e0 oxidation and chilling to secure this result. With a suitable circumambient medium it 'can be done.

One difficulty with plain oxidation is the fact that the reaction of free oxygen with the usual metals is exothermic, with the result that undesirable heat is liberated adding 'to the violence of the explosion.`

I have conceived the possibility of liberating or releasing from a suitable compound the reagent which is to unite with the metal by means of an endothermic reaction. This compound, as above explained, should be a high dielectric affected only by the heat of the arc and resistant of itself to current flow.

The reagent which I have thus far employed successfully is chlorine.. Chlorine reacts with metals in vapor form with great rapidity. I sce no reason why other halogens should not operate equally well and shall shortly conduct experiments to determine the suitability of the rest of the halogen group. I conceive fluorine, which is more active than chlorine, will perhaps give superior results. Bromine may also be used.

The particular substance which I have thus far successfully employed in carrying out m invention isfchlorinated naphthalene, whic is now found on the market under the trade name of Halowax. It appears on the market in various grades including a liquid and a solid or wax form.

Now in order to teach those skilled in the art how to practice my invention, I shall describe in conjunction with'the accompanying drawings specific embodiments of my invention.

In the drawings Fig. 1 is a longitudinalsection through a simple elementary form of a device embodying Vmy invention;

Fig. 2 is a similar view7 of a modification;

Fig. 3 is a longitudinal section of a fuse embodying my invention;

Fig. 4 is an end view of the same with the end cap removed as though taken on the line 4 4 of Fig. 3;

Fig. 5 is an end view of the terminal as though viewed from the left of Fig; 3;

Fig. 6 is a side elevational view of the active fuse element employed in Fig. 3;

Fig. 'Z is a longitudinal section of a modified embodiment of my invention;

Fig. 8 is a plan view of the holder for the active element;

Fig. 9 is a longitudinal sectional view of the active element shown in Fig. 7;

Fig. 10 is an end view of one of the caps of theouter shell of the fuse shown in Fig. 7;

Fig. 11 is a longitudinal sectional view of a spring operated fuse embodying'my invention;

Fig. 12 is a longitudinal sectional View of an expulsion type of fuse embodying my invention; and Y Fig. 13 is a diagram illustrating the fundamental method involved in the extinguishment of an are in accordance with my invention. v

Referring now to Fig. 1, I show therein a metal fuse elementsl having the enlarged terminals 2 3 and having a link 4 of reduced cross section preferably at the central part of the` fuse. The link 4 and the adjacent 55 portions of the fuse are contained Within 8.

sleeve 5 which is preferably made ofiiber or paper impregnated with a wax-like compound which, upon being heated frees chlorine or other halogen for cooperation with the metallic vapor of the fuse.

Within the sleeve or tube 5 there is a filling 6 of the same wax-like material.

The substance which I have successfully Its boiling point is from 610 to 650 de- I grees F. Its resistivity is of the order of 1500 1010 ohms per inch cube. Its specific gravity is about 1.589. .When brought to the boiling, or approximately the boiling point, it has low viscosity and readily penetrates fibrous bodies. At all normal temperatures f and under normal conditions it is neutral and noncorrosive in 'respect to metals. It is soluble in practically all organic solvent liquids and oils when heated therewith. It is insoluble in caustic alkaline and acid solutions except those that are powerful oxidizers It is anhydrous and non-hygroscopic and therefore will not draw or support a film of moisture-. Itis in its crystallization or in its solid form entirely free of moisture. It is a relatively soft solid, crystalline and translucent.

The chlorinated naphthalene may be secured in various grades, but the above form is the preferred form, since the solid form holds its shape under all normal atmospheric conditions. y

The paper or fibrous sleeve 5 is boiled in the chlorinated naphthalene to impregnate the same.

In Fig. 2 I have shown the elements of a fuse in which the sleeve 5 impregnated with chlorinated naphthalene is used alone, the heat of the arc caused by volatilizing ofthe fusible link 4 driving some of the arc extinguishing substance from the impregnated Walls of the tube 5 to fill the said tube 5 with active vapor. If desired, the ends of the tube 5 may be obstructed to assist in this aC- tion, or they may be completely closed upon the body of the fuse.

In the form shown in Fig. 1, the outer sleeve 5 may be made of other material, since the mass 6 of chlorinated naphthalene serves to perform the desiredfunction of extinguishing the arc independently of the evolution of any vapor or gas from the sleeve or envelope 5. n i

In Fi 3 to 6 I have shown a commercial form o cartridge fuse embodying my invention. In this form the outer protective sleeve 7 is preferably a bakelite tube or a tube of fiber impregnated with bakelite or una and of the terminal the like. The ends of the tube 7 are threaded as indicated at 8 and 9 and in each end transverse slots 10-11 are cut across the edge or margin of said sleeve 7.

An end plate member 12 having the disc 13 and theknife blade contact 14 is seated upon the end of the sleeve7 at each end. A

flanged ring 15 having the inturned margin 16 embraces the edges yof the disc member 13 and is threaded down onto the threads 8, as shown in Fig. 3. The disc member 13 has two key members 17 and 18 adapted to enter the slots 10 and 11 so as to anchor the knife blade member 14 rigidly in predetermined alignment. Thel construction of the sleeve 7 members cooperating therewith is identical at each end. The active element within the outer shell comprises a sleeve 20 preferably made of paper or liber `impregnated with chlorinated naphthalene of the character above described. A pair of discs 21 and 22 cover the ends of the sleeve 20 and these discs are slotted to receive the fusible element 1 having the. reduced cross section link 4. The ends of the fuse 1 extend through the discs 21 and 22 and are clinched or bent over `as shown in Fig. 4. For the purpose of equalizing the bearing of the disc member 13 against said clinched end, the end of the fusible'element 1 is preferably split and the two ends are bent over in opposite directions as indicated at 23 and 24 vin F ig. 4. lIt can now be seen that the renew-l able element shown in Fig. 6 may be inserted inside the outerv sleeve 7, the flanged ring 15 and the terminal element 12 being removed. The clinched ends y23-24 bear against the dise or plate portion 13 of the terminal element 12 at each end, and when the ring 15 is screwed down contact is thereby made between said ends of the fuse andthe knife blade terminals 14-14.

In Figs. 7 to 10 I have illustrated a cartridge form of fuse .'With'renewable element more particularly adapted for larger capacities. In'this form I provide an outer casing 25 from which the knife blade terminals 26-26 project. The outer casing 25 comprises a sleeve 27 preferably made of bakelite or bakelized fiber havingr its ends threaded to receive the caps 28-28, these caps being threaded to cooperate with the ends of the tube 27. The caps 28-28 contain central slotted disc members 29-29 having a slot l30 therethrough for receiving the knife blade terminals 2626. These slotted discs 29-are rotatable in the cap members 28-28. The cap members 28 may be of metalforthey may be of bakelite or bakelirzed liber or the like.

` `While both discs 29-29 are herein shown as rotatable,obviously one of them may be anchored and be non-rotatable with respect to its cap 28 if so desired. -Also it will be apparent that 'if desired the caps 28 may be this case I formed into the shape of flanged rings only, as shown in Fig. 3, and the discs 29-29 extended out to rest upon the ends of the sleeve 27 is so desired. The knife blade terminals 26-26 extend inwardly towards each other at their` inner ends, and these inner ends are shaped to form semi-cylindrical sockets to. receive a cradle member 30 which' is preferably a semi-cylindrical sleeve of hard fiber or the like. This sleeve of hard liber 30 is secured to the semi-cylindrical ends 31-31 of the knife blade terminals 26-26 by tubular rivets or the-like, as indicated at 32-32.

Preferably the kni-fe blade terminals 26- 26 andthe semi-cylindrical socket members 31 are formed integrally of a stamping of copper or brass. The shank of the knife blade contacts 26 adjacent the sockets 31-31 is enlarged to form shoulders 33-33 for limiting the endwise motion of the cradle in the outer lcasing 25.

These shank members are also provided with threaded openings 34-,34 for receiving clamping screws 35, the said clamping screws being adapted to pass through holes 36--36 in the ends of the active element shown in Fig. 9. The renewable element comprises the fuse 1 preferably having link of reduced cross-section 4 enclosed in an outer shell or casing` 37 having end caps 38-38.

The end caps and the shell 37 may be made of paper or fiber impregnated with chlorinated naphthalene, and the said fuse element 1 supported in said end caps, which are in turn connected together to the end sleeve 37. If desired a filling 38 of the solid wax-like chlorinated naphthalene maybe employed within the sleeve37.

For the renewal of the active fuse element, the renewable member is released 'at the screws -35 and a new element dropped into the cradle shown in Fig. 8, whereupon the ends of the fuse 1 are clamped by the screws 35, then one end or knife blade terminal 26 is passed through a slot in the disc 29, then the cap at thev opposite end with its disc 29 is passed over the adjacent knife blade contact 26 andthe cap member 28 is screwed up tight on the outer sleeve 27.-

In Fig. 11 I have shown a fuse in which the fuse termin`a-ls .are separated by means of a spring whemthe fuse element melts. In provide an outer container formed of a piece of lass tubing I 41;Which has a cap 42 prefera ly of brass 'cemented upon the lower .end ofthe' sameor 'otherwise suitably secured thereto, a'nd a. sleeve or ferrule 43 cemented or otherwise secured to the upper end thereof. The sleeve 43 extends beyond the end of the glass sleeve 41 to provide a seat for the disc-like capmember 44 which preferably has a flange 45 turned up around the rim of the same to provide a wider sealing surface. The central p art of the cap 46 is preferably bowed up, and under the tension of the spring 47, which acts upon it, this central arched portion 46 is pulled. downwardly, tending to spread the edges of the disc into the side engagement with the counterbore of the ferrule 43.

The fuse element comprises a link 48 preferably having a small cross-section at the point where the blowing is to occur, and conanected to suitable metallic terminals 49 and 50. These terminals and the fuse element are imbedded in a mass or filling 51 of chlorinated naphthalene in wax form, said filling being contained within a sleeve 52 formed of fiber or paper impregnated with the same substance. The terminal 50 is connected to the sleeve 52 by a transverse pin 53 extending through both of said elements. The'spring 47 is secured to the lower end of the terminal member 50 au d to an anchor 54 formed ou the cap member 42. The spring 47 is placed in tension and the upper terminal member` 49 is passed through an opening in the cap member 46 and is there anchoredl as by soldering or by forming a button or the like upon the end of the terminal 49 which is then drawn down tight into engagement with the edges of the hole formedin the cap member 44.

It is not essential that the casing be absolutely fluid tight, but it is desirable that it be so to the extent of excluding moisture.

Upon blowing of the fusible portion 48, the arc extinguishing material, i. e., the chlorinated naphthalene, is immediately available to attack the substance of the arc and form with it non-conducting compounds, which, being chilled by the presence of the mass ot material and the sleeve outside of the same, becomes a non-conductorof electricity. At the same time, the terminals are separated to increase thelength of the are and, hence, its vulnerabilit to attack. The sleeve 52 with its lilling 51 o chlorinated naphthalene is ,drawn down with the spring 47 so that the movable terminal 50 is surrounded by a bath or mass of the chlorinated naphthalene regardless of the position of the fuse.

Obviously, the upper end of the sleeve 52 might be attached to the cap member 44, and the terminal 5() pulled down through the mass of arc extinguishing material, but this would expose the glass sleeve 41 to the heat of the are directly, and that is not desirable.

To .avoid exposing the upper end of the glass sleeve to the heat ofl the arc, I provide a sleeve or lining 56 of paper or fiber impregnated with -chlorinated naphthalene at the upper end of the glass sleeve wherethe glass might be exposed to the arc by a downward vmovement of the movable sleeve 52.

Obviously, as soon as the tension of the spring leaves the disc 44, its tendency to bind the counterbore of the errule 43 is reduced, and any tendency to form high pressure Within the outer casing 40 will result in minal 49. Preferably the spring 47 is shunt' ed by a iexible conductor.

In Fig. 12 I have shown an expulsion type of fuse embodying my invention. In this case I employ a sleeve of insulation as shownat 57, this sleeve being formed of bakelized fiber, porcelain or glass. To the lower end of the sleeve 57 there is attached a ferrule 58 with a terminal screw 59 for clamping the lower end 60 of the flexible fuse terminal 6l to the ferrule 58. To the upper end of f the sleeve 57 I connect an explosion chamber member 62. This is preferably formed of a metal casing cemented or otherwise secured upon the up er end of the sleeve 57 and having a threa ed opening at its upper end in alignment with the bore of the tube 57 and normally closed by a threaded plug 63. To the threaded plug 63 on its lower end I connect a fuse terminal 64, and between the fuse terminal 64 and the fuse terminal 61 a fusible link 65 is connected. On the outside of the lower end of the terminal 64 and the upper end of the terminal 61 I mount a sleeve 66 of paper impregnated with and illedwith a mass7 of chlorinated naphthalene as indicated at 6 i Upon blowing of the active element 65 the arc which is formed is immediately attackedv by the arc extin uishing material in solid form, which, by t e heat of the arc, is melted and vaporized to some extent. The pressure which results from the formation of the arc expels or in part expels the paper sleeve 66 with its filling 67 of wax-like arc extinguishing material. If the explosion is particularly violent the entire sleeve with its mass of material and the terminal 61 may be expelled through the sleeve 57.

The fuse may be refilled by removal of the threaded plug 63 and loosening of the terminal 59 to release the portion 60 of the flexible terminal and an entirely new fuse and terminal attached to a plug such as 63, dropped down through the open end of the chamber 62 and down through the sleeve 57. The upper terminal 64 may be lixedly secured to the plug 63 or releasably secured to the same, thisvfeature being optional.

In all of the forms illustrated, the arcis brought into Contact with a mass of chlorinated naphthalene preferably in the solid form. 'Obviously within my invention the` liquid form Vmay bev employed, care being taken to make the cdntainer sufficiently tight to retain the liquid form. The contact of the heat of the arc with the chlorinated naphthalene dissociates and the halogen element thereof attacks the metal vapor of the are, forming non-conducting compounds which,

being chined and Sabiiized by the Surrounding relatively cold mass, do not further disintegrate under the electric arc, with the result that the fuse ei'ectually prevents sustained current flow.

To illustrate the fundamental action involved, I show in Fig. 13 diagrammatically two metallic terminals 70 and 71 between which an arc is formed within the sleeve or housing 72 by current supplied through a suitable source as indicated at 78. An inlet nozzle 74 is directed into the space in which the arc is formed and this is connected by a pipe 75 through a control valve 76 with a tank of chlorine gas under high pressure,v as indicated at 77. Assume that the arc is .formed between the terminals 7 0I and 71 in a relatively confined space. I thereupon admit at high velocity and at relatively high pressure chlorine gas which displaces the atmospheric air tending, by its chilling effect, to reduce the temperature within the container 72 and tending, by its chemical effect, to cornbine with the metal which is in extremely susceptible form to chemical action, whereby non-conducting compounds are formed faster than meta-l can be liberated from thel terminals 70 and 71, with the result that the arc is extinguished. r It will be seen that it is desirable to employ las an activeelement a material which will have the ability to attack the active metal or other conducting substance in the arc at a temperature less than the temperature of the electric arc and with great rapidity.

Preferably such action should not add heat to the mass, but should require a temperature less than the temperature of the arc for its best or optimum condition. The chlorinated naphthalene requires heat to break it down to free the chlorine, and this, therefore, forms an ideal combination, since the reaction is .endothermic to the extent of requiring the heat of the arc to liberate the chlorine, which chlorine in turn attacks the arc to form a compound which is non-conducting, or relatively so, and which, due to the extraction of heat therefrom, becomes stabilized and will not again dissociate.

I do not intend to be limited to the details shown and described, nor to the specific material'which I have above described in detail,

since I am convinced by my experiments that fluorine, as an active element, would be even more effective for this purpose.

It may be that other negative elements or radicals combining with the metal of the fuse will be equally effective in forming a non-conducting compound to extinguish the arc, and these, if discovered, I beg to insert in this description hereafter as coming within the broad scope of my invention.

Preferably the metals which I employ for the fusible link are such as aluminum, zinc, tin and lead, which are Very quickly attacked densation product and an inner lining of fiber impregnated in a solid waxy halogen derivative of naphthalene, and a fusible link within said container.

2. In combination, an outer sleeve having a metallic cap at one end, a metallic ferrule at the other, said ferrule having a portion extending beyond the end of the sleeve, a removable closure for said end of the ferrule, a spring secured to the cap within the sleeve, a pair of terminals, one of which is connected to the spring, the other of which is connected to the ferrule, a fusible link between said terminals and a filling of solid arc extinguishing material surrounding said fusible link, said material being converted from solid to liquid and from liquid to gas by absorption of the heat of the arc formed Awhen said link ruptures to quench that arc.

3. In combination, an outer sleeve having a metallic cap at one end, a metallic ferrule at the other, said ferrule having a portion extending beyond the end of the sleeve, a removable closure for said end of the ferrule, a spring secured to the cap within the sleeve, a pair of terminals, one of which is connected to the spring, the other of which is connected to the ferrule, a fusible link between said terminals and a filling of solid arc extinguishing material surrounding said fusible link, an inner sleeve for containing said solid mass of arc extinguishing material, said innersleeve being connected to the spring and movable thereby together with the movable terminal, and a third sleeve impregnated in said arc extinguishing material and interposed between said inner and outer sleeves to protect thei latter from rupture when said link is ruptured.

4. In combination, an outer sleeve element, closure members for each end of the sleeve, a pair of terminal members electrically connected to each of the closure members, one of said terminal members being movable, a spring connected to the movable terminal member -for separating it from the other terminal member, means for supporting a nal members projecting from said cartridge, a mounting therefor consisting of a cup-like body conforming to the contour of said cartridge with terminal pieces projecting from opposite ends of the body, to which pieces said cartridge terminal members are attached, and a casing surrounding said cartridge and body, from which casing said terminal pieces project.

6. In combination with 1. fuse cartridge having a fusible member whose middle portion is encased in a body of chlorinated naphthalene and Whose end portions form terminals projecting therefrom, a mounting com-l prising knife blade terminal members spaced apart by a cradle in which said cartridge rests, means for fastening said terminals to said knife blade members, and means removably supported on said members for encasing said cartridge and cradle.

7. In combination with a fuse cartridge having a fusible member Whose middle portion is encased in a body of chlorinated naphthalene and whose end portions form terminals projecting therefrom, a mounting comprisin0r knife blade terminal members spaced apart tby an insulating cradle 'in which said cartridge rests, means for fastening said terminals to said knife blade members, and means removably supported on said members for encasing said cartridge and cradle.

8. In combination with a fuse cartridge having a fusible member whose middle portion is encased in a cylindrical body of chlorinated naphthalene and whose end portions form terminals projecting therefrom, a mounting ycomprising knife blade terminal members spaced apart by a semi-cylindrical insulating cradle in which said cartridgerests means for fastening said terminals to said knife blade members, and means removably supported on said members for encasing said cartridge and cradle.

9. As an article of manufacture, a fuse comprising a casing having removable ends, contact strips extending from said ends, an insulating cradle within said casing supported on the inner ends of said contact strips, and a fuse cartridge supported in said cradle and having terminals electrically connected to said contact strips.

l0. In combination with a fusible metal encased in a body of chlorinated naphthalene and projecting from the ends thereof, an open end insulating tube into which said body fits, a metal expulsion chamber attached to one end of said tube, a plug attached to one of the projecting parts of said fuse and threaded into said chamber to close it, a metal ferrule attached to the outside of the other end of said tube, and means for attaching the other of said projecting ends of the fuse to said ferrule without closing the end of said tube to thereby permit the pressure formed by anl arc in said naphthalene to expel said body from the tube.

11. In an expulsion type fuse, an insulating tube, a metal expulsion chamber attached to one end of said tube, said chamber having a threaded opening opposite the end of said tube, a metal band or ferrule encircling the other end of said tube, a fuse cartridge comprising a fusible strip encased in a body of chlorinated naphthalene, a threaded plug attached to one end of said strip, said plug being threaded into said opening to close the expulsion chamber when said cartridge is in place, and a contact strip attached to said fusible strip and ferrule, said strip leaving the end of the tube open to permit expulsion of the naphthalene body by the gases formed therein by the fusing of said fusible strip.

12. In an expulsion fuse, an outer tube with an expulsion chamber attached at one end thereof,a ring or ferrule encircling the other end of said tube, a fusible clement attached to said ferrule and chamber, an inner tube loosely fitted in said outer tube and surrounding that portion of the fusiblev element within said chamber, and a filler Within said inner tube and around said fusible member, said filler being Volatilized by the arc formed by the fusing of said'elementto form an arc quenching gas, the pressure of which expels said inner tube from said chamber through said outer tube to thereby separate the ends of said fusible element to expedite the extinction of said arc by said gas.

13. In an expulsion fuse having an exn pulsion chamber closed at one end by a removable plug, an open ended tube extending from said chamber, a fuse cartridge in said chamber, a connection between one end of said fuse cartridge and said plug, a ferrule surrounding the open end of said tube, a connection between the opposite end of said cartridge and said ferrule, and means with in said cartridge acted upon by the arc caused by the fusing of said fuse to form an arc quenching gas the pressure of which expels said cartridge from said chamber through said tube.

In witness whereof, I hereunto subscribe my name this 21st day of December, 1927.

CLARENCE RINGWALD. 

